I'm trying to create a datamodel in the Oracle Data Modeler module that is available in Oracle SQL Developer. I would like to maintain my data dictionary from this model. To do this (I think) I need a generated DDL file for which the attributes are not longer than 30 characters.
I have just discovered Oracle SQL Developer and am completely new to creating these kind of models. What I have done so far. I have created a logical model and have engineered it to a relational model. From the relational model I can then generate DDL scripts that I can run on the database to make the changes I want.
When doing this I run into a problem. When engineering the logical model to a relational model I can see that the foreign keys I have made become more than 30 characters. This is because it seems to generate the name as (see picture)
From searching it seems you should be able to fix this with naming standard templates. I have looked for this menu option but can't find it. I have found the name abbreviations functionality for which you can upload .csv files but I think this is for something different.
Rightclicking on the logical model in the datamodeler browser view gives me the opportunity to Apply naming standards, but this gives me a message that I should turn off the keep as the name of the originating attribute option (see picture). I have looked for this but can't find this option.
My version of Oracle SQL Developer is 4.1.3.20, Build MAIN-20.78.
Please let me know if my story is not clear. Thanks.
Generated column name
Applying name standards message
You will find the option under Tools/Preferences/Data Modeler/Model/Logical
Related
I have been using Database First Entity Framework (EDMX) and SQL Server Data Tools Database Projects in combination very successfully - change the schema in the database and 'Update Model from Database' to get them into the EDMX. I see though that Entity Framework 7 will be dropping the EDMX format and I am looking for a new process that will allow me to use Code First in Combination with Database Projects.
Lots of my existing development and deployment processes rely on having a database project that contains the schema. This goes in source control is deployed along with the code and is used to update the production database complete with data migration using pre and post deployment scripts. I would be reluctant to drop it.
I would be keen to split one big EDMX into many smaller models as part of this work. This will mean multiple Code First models referencing the same database.
Assuming that I have an existing database and a database project to go with it - I am thinking that I would start by using the following wizard to create an initial set of entity and context classes - I would do this for each of the models.
Add | New Item... | Visual C# Items | Data | ADO.NET Entity Data Model | Code first from database
My problem is - where do I go from there? How do I handle schema changes? As long as I can get the database schema updated, I can use a schema compare operation to get the changes into the project.
These are the options that I am considering.
Make changes in the database and use the wizard from above to regenerate. I guess that I would need to keep any modifications to the entity and/or context classes in partial classes so that they do not get overwritten. Automating this with a list of tables etc to include would be handy. Powershell or T4 Templates maybe? SqlSharpener (suggested by Keith in comments) looks like it might help here. I would also look at disabling all but the checks for database existence and schema compatibility here, as suggested by Steve Green in the comments.
Make changes in code and use migrations to get these changes applied to the database. From what I understand, not having models map cleanly to database schemas (mine don't) might pose problems. I also see some complaints on the net that migrations do not cover all database object types - this was also my experience when I played around with Code First a while back - unique constraints I think were not covered. Has this improved in Entity Framework 7?
Make changes in the database and then use migrations as a kind of comparison between code and the database. See what the differences are and adjust the code to suit. Keep going until there are no differences.
Make changes manually in both code and the database. Obviously, this is not very appealing.
Which of these would be best? Is there anything that I would need to know before trying to implement it? Are there any other, better options?
So the path that we ended up taking was to create some T4 templates that generate both a DbContext and our entities. We provide the entity T4 a list of tables from which to generate entities and have a syntax to indicate that the entity based on one table should inherit from the entity based on another. Custom code goes in partial classes. So our solution looks most like my option 1 from above.
Also, we started out generating fluent configuration in OnModelCreating in the DbContext but have swapped to using attributes on the Entities (where attributes exist - HasPrecision was one that we had to use fluent configuration for). We found that it is more concise and easier to locate the configuration for a property when it is right there decorating that property.
I was able to define a custom programming language in Enterprise Architect with custom data types by navigating to Project > Settings > Code Engineering Datatypes.... When I create a MDG file, I have the option to include the programming language definition, and as far as I can tell, this is working - at least, in a new project that uses the MDG file, I can see the programming language.
Now I would like to have the same behavior for DBMS and database datatypes defined through Project > Settings > Database Datatypes.... From my tests, I get the impression that these types are not automatically included in the MDG file, and I haven't found a trivial way to include them. Is there a way to add the database datatypes to the MDG file as well? If not, is there a way to achieve the same result through the automation interface, e. g. by writing an add-in that creates the DBMS and the associated datatypes?
Going the MDG Technology way, the answer appears to be no. It's possible to trick EA (11) into exporting DB types in an MDG Technology, but even if they're in there, they will be ignored in projects that use the MDG Technology.
DB types and code engineering (or, sometimes, "programming language") datatypes are both stored in EA's t_datatypes table. The same product name can be used for both a programming language and a DB engine.
It looks like the MDG Technology Wizard scans this table looking for rows with "Code" in the Type column during the setup (Code Modules wizard page), but when the time comes to write the actual datatypes into the output file, it retrieves all rows with the specified ProductName.
This means that if you create a DB product and populate it with a set of datatypes, and then create a programming language product with the same name but just a single dummy datatype, your DB types will be included in the MDG Technology XML file along with the dummy type.
However, it appears that while the regular properties dialog (for classes etc) checks the loaded MDG Technologies in addition to the t_datatypes table in order to populate the Language drop-down list, the specialized properties dialog for database tables does not check the MDG Technologies when populating the corresponding Database drop-down. So even though the datatypes are in the file, you can't use them.
Going the Add-In route, the answer is yes.
Have your Add-In respond to the EA_FileOpen event and check the Repository.Datatypes collection to see if your DB types are installed and if not, add them.
You don't actually need to write an Add-In if you don't want, you can write an in-EA script. The only thing an Add-In can do that scripts can't is respond to events (which is why those are listed in the Add-In Model section of the help file). So with a script you would have to trigger the function manually.
There is also an API to manage project's reference data of which code / DB datatypes is one category, but it only gives you control of some of the categories (eg requirement types and constraint types), and the datatype category is not one of them.
The fact that EF does not handle the hierarchyid MSSQL data type is widely known. The problem using the AdventureWorks sample database to generate an EF data model caused by a table using hierarchyid is also quite well known and widely reported. A good proposed workaround, for read only scenarios, is to use a view in place of the 'offending' Production.Document table, and cast that column to a more acceptable type, like 'nvarchar'.
However, it seems the only avenue open for creating a Code First data model is to brutally remove the table altogether, as the EF Power Tools code generator skips the pleasantries allowing a user to select which tables to include in the model. So here, even using a view won't work, because the view depends on its base table.
Does anyone know a workaround for this that doesn't involve modifying the T4 templates by hard-coding to skip this table?
Yes, install VS 2013 Update 4, which include the latest EF Tools, and use the Code First Model from Database feature, it allows you to select which tables to generate.
I am using EF Code First in a project with an existing Database, all works well and so far I have been creating the class for each table manually (as they have been very small) but getting to the larger tables I can only assume there must be a better way to 'import' or 'convert' the tables fields into a class somehow. Had a search around and can't really find what I'm looking for.
To clarify I want to keep it Code First.
EF Power Tools contains reverse engineer feature for this purpose.
If we've been using an Entity Framework 4 model for some time, and we eventually want to switch the underlying database to a different vendor's product (say, from SQL Server to MySQL), is it simple to adjust the table and column mappings in the entity model without needing to update any of the entity class code?
We're trying to design code that is as database agnostic as possible, so I'd like to know in advance how much trouble we're in for if we ever switch our databases around. Ideally, we'd like to not have to touch our applications that use our entity classes. I can't seem to find any way in the entity designer or XML editor to adjust the underlying database column names without it giving me an error.
(I can, however, edit the entity's property names in the designer while leaving the database column names alone, but that's the opposite of what I need.)
Thanks!
EDMX is not database agnostic. SSDL part of EDMX is tightly coupled with database server (in case of MSSQL even with its version). You need separate SSDL for each supported database server.
I don't understand how changing column names relates to database agnostic model. Reverse is true! If you need your database to have different column names for different server products you need separate mapping for each of them!
Changing column names when using model first is possible only if you modify T4 template used for generating database creation SQL script. But every time you create that script designer will delete whole your storage description (SSDL) and mapping (MSL) and replace them with a new one.
The easiest way to have database agnostic code is using code first but even then you can have problems with some type and feature inconsistency among servers.
If you want database agnostic ORM you should probably check NHibernate.